The U.S. Court of Appeals for the Federal Circuit, in a 2-1 ruling, largely upheld the ability of Myriad Genetics Inc. MYGN +4.88% to obtain patents on two genes that can signal if a woman faces greater risk of developing breast cancer or ovarian cancer. Myriad's patents allow the company to be the exclusive U.S. commercial provider of genetic screenings for the diseases. Thursday's ruling was the latest chapter in a long legal battle between Myriad and medical organizations that have argued the Salt Lake City company is trying to patent "products of nature," which can't be patented. The challengers say the gene patents interfere with medical treatment and scientific research, assertions that Myriad disputes.

The appeals court issued a similar ruling last year. But earlier this year, the U.S.Supreme Court ordered the Federal Circuit to reconsider the Myriad case in light of a Supreme Court ruling in a different patent case that tightened rules on medical-testing patents.

On Thursday, the appeals court said the Supreme Court's recent ruling didn't require it to retreat. "Permitting patents on isolated genes does not pre-empt a law of nature," Judge Alan Lourie wrote in the Federal Circuit's lead opinion.